Agriculture in the Southwest United States is very important economically in that region. Much of the land, and most (85%ish) of the fresh water in the region is used on agriculture. The region gets less rainfall and is warmer than most other areas in the United States, so farming techniques have evolved to accomodate for a drier climate with less permeable soils. The Native Americans of the region had many different methods of farming, and grew many different crops than what is typically grown today in the Southwest by industrial farmers.
The three main watersheds of the southwest United States are the Colorado River Basin, the Great Basin, and the Rio Grande Basin. The Colorado River Basin includes parts of California, Utah, Arizona, New Mexico, Colorado, and Wyoming. The Colorado River is the largest river in the Southwest United States. The Great Basin watershed includes parts of southern California, most of Utah, the northwest half of Nevada, and parts of Oregon and Idaho. The Rio Grande Basin includes most of New Mexico, some of western Texas, and a small portion of Colorado.
Almost all of Arizona drains into the Colorado River. Most of New Mexico drains into either the Rio Grande or the Pecos, its tributary. Other watersheds of New Mexico include the Canadian River in the northeast, the San Juan in the Northwest, and the Gilla (tributary of Colorado River) in the southwest.
The southwest United States has a very rugged and diverse geography.
There are two main physiographic regions which Arizona is a part of. North and east Arizona is part of the Colorado Plateau, and the Basin and Range is in southern and western Arizona.
The Colorado Plateau is a flat, elevated land of soft sedimentary rock about 5,000 to 9,000 feet above sea level. Rivers cut deep canyons and gorges into the plateau, the largest of which is the Grand Canyon of the Colorado River, which is in the northwest corner of Arizona. There are also scattered mountains and mesas throughout the mostly flat plateau. The highest mountains in Arizona are the San Francisco Mountains in the northern part of Arizona.
Almost all of Arizona lies in the Colorado River Basin. The largest tributary to the Colorado in Arizona is the Gila, which crosses the southern part of the state and meets the Colorado River at Yuma. The Salt River is the principal river of the Gila. There is usually little or no flow of water at the junction of these rivers because of heavy use upstream.
In Arizona, there is little rainfall and low humidity. Annual precipitation varies from 2 to 14 inches throughout most of the state. The mountains of Arizona can receive as much as 30 inches. There are huge fluctuations in temperature between day and night. Temperatures frequently reach 100@F in the summer, and they can fall as low as 0@F in the winters in the Plateau Region. The Plateau Region is generally cooler then the southern Basin and Range.
Arizona is one of the sunniest states in the United States.
New Mexico is covered by four main regions: the Rocky Mountains, the Great Plains, the Colorado Plateau, and the Basin and Range. The Rocky Mountains cover north-central New Mexico and consist of southward mountain ranges coming from Colorado. The three main mountain ranges are the Sangre de Cristo Mountains in the east and the San Juan and Jemez mountains in the west. Between these western and eastern ranges lies the Rio Grande Valley. The mountains of northern Arizona stand 10,000 to 13,000 feet high.
The Great Plains are in eastern New Mexico. The northernmost section of this region is hilly and contains some lavacapped mesas and buttes. South of the Canadian River, the land is very flat. This region is referred to as the Llano Estacado, or the Staked Plain. West of the Llano Estacado is the Pecos Valley which stretches about 250 miles along the Pecos River. The Pecos Valley is low in elevation and flat, with some mesas and canyons. The lowest point in the state, Red Bluff Lake on the Pecos River, is 2817 feet above sea level.
The Basin and Range region is in southwest New Mexico and a thin stretch northeast to Santa Fe. This region consists of barren mountain ranges spaced with dry basins. Most mountain ranges in this region are rounded and relatively low. The basins of this area contain salt flats, sand dunes, and lava flows.
Most of New Mexico's main rivers carry little water for most of the year, with varying seasonal flows. Because of the undependable water supply, some rivers in New Mexico have been dammed to provide water for irrigation, power, domestic use, and recreation. New Mexico is very dry in most places except the mountains. The climate is known as a middle-latitude steppe climate.
The mountains of New Mexico receive from 20 to 25 inches of rainfall per year. The Great Plains receive from 12 to 16 inches, and the southern and western portion of the state receive as little as 8 inches. Most of this rainfall occurs during summer thunderstorms.
On the mountain slopes of Arizona, there are forests of Ponderosa pine, firs, and other evergreen trees. These trees, especially the Ponderosa pine, are the main source of Arizona's commercial timber. At lower elevations, the main natural trees are the pinyon, juniper, and oak.
Compare/contrast different techniques...how much each produces comparably
Laws regarding agriculture in the area, future possible laws/regulations, history of the regulation of agriculture in the area.
Compare/contrast different techniques/methods and their environmental impact
http://www.fao.org/docrep/012/i0372e/i0372e08a.pdf Development of Dryland Farming in Various Regions... has a section about North America. Just a brief history of why and who, not much about actual techniques
https://portal.sciencesocieties.org/Downloads/pdf/B40714.pdf Dryland Agriculture-Second Edition... only has the Foreword, Preface, Table of Contents, and Contributors... book might be helpful, the preface could be too
http://pdf.usaid.gov/pdf_docs/PNABN914.pdf Improving the Sustainability of Dryland Farming Systems: A Global Perspective... explains sustainability, soil productivity, opportunities/limits of dryland farming, and different pespectives and stretegies. Looks very informative, not too long.
http://stephenschneider.stanford.edu/Publications/PDF_Papers/Schlenker_Hanemann.pdf The Impact of Global Warming on US Agriculture: An Econometric Analysis... talks about dryland agriculture a little
http://www.southwestclimatechange.org/impacts/people/agriculture Agriculture... talks about climate change and its potential impacts on agriculture in the SW
http://www.crs.wsu.edu/outreach/rj/agsurvey/southwest.html A bunch of tables comparing agriculture in the southwest region to Washington State. Although I think it could be talking about southwest Washington. There's no explanation on the page...
http://southwestfarmpress.com/moisture-management-becomes-critical-southwest-agriculture Moisture Management becomes critical for Southwest agriculture... An article about how it's important to conserve water in the region
http://www.cabrillo.edu/~crsmith/southwest.html Native Peoples of North America: Agricultural Societies in Pre-European Times: Southwestern US and Northwestern Mexico... description of different tribes, how they lived, and what kind of techniques they used to grow food (ex: subsurface irrigation, terracing)
Enduring Seeds: Native American Agriculture and Wild Plant Conservation (Gary Nabhan)...
http://geography.howstuffworks.com/united-states/the-southwestern-united-states.htm Description of geography in certain regions of Arizona, New Mexico, (OK & TX)
http://www.jswconline.org/content/51/4/280.extract Sustainable Agriculture in the Southwest United States and its relationship to landscape planning... Just an excerpt, but looks useful if I can find the full document
http://southwestfarmpress.com/grains/american-agriculture-answering-call-energy-independence American Agriculture answering the call for energy independence... Article with statistics and qualitative analysis, useful.
http://www.epa.gov/agriculture/ag101/cropmajor.html Major Crops Grown in the US... if you go back on the page you can find farming systems
http://www.motherearthnews.com/Organic-Gardening/Best-Southwest-Region-Garden-Crops.aspx Top Crops: Southwest... More about personal gardens though, still useful just not industrial scale ag
http://geochange.er.usgs.gov/sw/changes/anthropogenic/cropland/ Land Use Trends in the Southwestern US... what crops are grown where
http://maps.howstuffworks.com/united-states-watersheds-map.htm